Plasma neurotransmitters, blood pressure, and heart rate during supine resting, orthostasis, and moderate exercise in dysthymic depressed patients

Dysthymic depressed patients showed platelet-serotonin (pS) + plasma-free serotonin values greater than normal as well as plasma noradrenaline values lower than normal during supine resting period (0′). Conversely, no significant differences were observed in the 0′ values of any other of the measured parameters: systolic, diastolic and differential blood pressure (SBP, DBP, DP), heart rate (HR), adrenaline (Ad), dopamine (DA), cortisol, and platelet aggregability between patients and controls. Although patients showed the normal DP reduction at orthosthasis (1′), this was not prevented by atropine as it does in controls. Patients but not normals showed significant rises of DBP at orthostasis and exercise (5′) periods, which were positively correlated with NA rises. On the contrary, the abnormally raised resting fS values registered in patients showed progressive and significant reductions throughout the test that were negatively correlated with DBP-NA values. Adrenaline did not show the normal 5′-fS peak. The above findings suggest that dysthymics show hypoactivity of the two branches of the sympathetic system (neural + adrenal) along with hyperparasympathetic activity. Furthermore, their low NA + high pS values contrast with the high NA + low pS registered in major depressed subjects.